I'm a fan of hard work. If you're not particularly smart, or talented, or skilled (in short, if you're me), then hard work may be your only competitive advantage.

If you can't outthink or outsmart or out-innovate other people, well, you can at least outwork them.

As Elon Musk once said, "Nobody ever changed the world on 40 hours a week." To Musk, 80-hour weeks are sustainable, with occasional 100-hour spikes.

But Musk's idea of what is sustainable doesn't align with a significant body of research that reveals the physical toll associated with consistently working long hours.

A 2014 meta-analysis of more than 530,000 people published in Lancet found that people who work 55 hours per week have a 33 percent higher risk of stroke compared with those who work "only" 40 hours per week.

A 1998 study published in BMJ found that people who work 11 or more hours per day (basically, 55 hours per week) are more than twice as likely to have a heart attack; in rough terms, every hour over nine per day increases the risk. Another 2014 study published in Lancet found that people who work 55 hours or more per week in jobs that involve physical labor are more likely to develop type-2 diabetes.

And then there's this: A study published just days ago in Environment International estimated that nearly 750,000 people died in 2016 from stroke and heart disease as a result of having worked at least 55 hours a week, and that between 2000 and 2016 the number of deaths from heart disease and stroke due to working long hours increased by 42 percent and 19 percent, respectively.

The list goes on. Increased risk of sleep disturbance. Depression. Emotional and physical burnout.

And not only for you; your employees likely face the same risks. A recent ADP survey found that the average worker puts in more than 9 hours of unpaid overtime a week, and one in 10 put in over 20 hours per week.

So yeah: Plenty of people embrace the "hustle harder" lifestyle.

And it may, slowly but surely, be killing them.

Keep in mind work itself isn't necessarily to blame. Generally speaking, the more you work, the less time you have to take care of yourself. Put in 10 or 12 hours a day at work -- even if you're working from home and spread those hours across the day and evening -- and you're less likely to exercise. Less likely to eat healthy.

Less likely to take physical -- and, just as important, mental -- breaks. Less likely to spend time with family and friends. Less likely to actively mitigate the stress you naturally experience.

That's the real problem. A 2018 study of 80,000 people found that those who said they did "any strength training at all" on a regular basis were 23 percent less likely to die prematurely and 31 percent less likely to die of cancer. A 2018 study found that regular jogging can lowering the risk of dying from any disease by 40 percent. Without regular exercise, the negative impact of sitting all day goes unchecked.

And then there's this: A clinical review of nearly 150 studies found that people with strong social ties had a 50 percent better chance of survival, regardless of age, sex, health status, and cause of death, than those with weaker ties.

The key word is "strong." Superficial, distant, and less than meaningful relationships can lead to feelings of insecurity and loneliness, which can increase your risk of illness and death just as much as obesity, alcoholism, and smoking.

Health and fitness and maintaining strong social ties pay huge mental and physical dividends. But they take time.

And the more hours you put in, the less time you have.

Even so, instantly reducing the number of hours you work may not be feasible. Launching a business can be overwhelming. Building a business can be overwhelming. (Working for someone else can be overwhelming.) You may not be able to control the number of hours you work.

But you can -- in fact, you need -- to control what you do with a few of your non-work hours every week.

The more hours you work, the more you need to take care of yourself. The more hours you work, the more you need to exercise regularly. The more you need to eat healthy. The more you need to actively plan ways to spend time with family and friends, and to nurture the relationships that really matter.

Because if you don't, you're less likely to be around as long to enjoy those relationships.

Elon Musk may be right. We may not be able to change the world unless we work 80-hour weeks. But at the same time, it's hard to imagine any of us will spend our last days wishing we had spent more time at work.

Or not caring that we didn't take better care of ourselves.